– Lync users should have the latest build of the 2010 or 2013 clients – available from the downloads section in the Office 365 portal

Adding a Skype user to Lync is relatively straight forward:

When chatting to them you will see the Skype icon next to their name so you will see the difference:

Part of the challenge I had in getting this to work between my Lync and Skype accounts is that my Skype/Live account uses a vanity domain – so I couldn’t simply add the account with its actual Microsoft account address. The format required when someone use a vanity/custom domain for their Microsoft account is:

The availability of Lync to Skype federation is exciting, as many organisations I speak with are already using Skype for business purposes before switching to Office 365 and Lync Online. This now means that they don’t have to leave those external contacts behind when making the switch.